mobile data shows error

I bought the device iPhone XS in USA and I am using it in India, Puducherry. I updated the software one week back but it was not updated at several attempts. Suddenly after some more try. I tried it successfully through Mac. While updating in several attempts i think that it lost cellular network connectivity. I also tried with a different service provider’s SIM but could not get the SIM connectivity. I tried with the local service provider. They are suggesting as it is hardware issue the could not solve it in India and to go for a exchange scheme. Hence I request your valuable advise and solution to remove the problem.